How to undo a union later in project and on imported objects

How do I undo a union on an object later in the project when I want to edit pieces?

Also, how do I ungroup an imported STL file so I can edit pieces of it. Right now it imports as one grouped object.

Thanks in advance!

All the elements have to be at the root of the layers menu, if you have them grouped together when exporting, it will be a unique object impossible to ungroup in the .STL format

Right but unless you do a union of objects all connected and then immediately hit the undo arrow, you will be stuck with an object that you can’t ungroup for editing. I figured out after I did a union and later in the project that I need to edit an object that I can’t unless I van undo a union…is there another way besides remaking said object??

Thanks for your time

Also, it’s not possible to undo a union later in the project. We usually recommend that is the last step when done editing the individual model parts. Thank you for your understanding.

In this case I don’t know what you could do, I still haven’t found myself in that situation, you could edit the part you need as a single object and then export it, or make the adjustments in shapr3D and export the whole set again.
not finding myself in that situation I can not help you in more